A possible role for intercisternalelements in the formation of secretory vesicles in plant golgi apparatus

Structures superficially resembling dictyosomes were present in guinea pig primary spermatocytes and in spermatids in late stages of development. The dictyosome-like structures (DLS) were composed of 2 to 17 saccules. Each saccule averaged about 20 nm in thickness (membranes plus lumen) and 400 nm in diameter and was separated from adjacent saccules in a stack by an intersaccular space of about 12 nm. Single saccules separated from the DLS were also present. Tubules up to 60 nm in diameter were continuous with the edges of the saccules and sometimes extended for several micrometers into the cytoplasm. The membranes of the tubules appeared similar to the saccule membranes. Some DLS saccules and tubules had coated vesicles attached to them. A distinguished feature of DLS was the presence of microtubule-like structures, about 10 nm in diameter, that bridged the inter-saccular spaces. Some of these bridging structures appeared continuous through one or more saccules. The bridging structures were often arranged in linear arrays or in clusters of three to four. The membranes of the DLS appeared tripartite but stained differently from the membranes of the endoplasmic reticulum or Golgi apparatus. The inner (luminal) leaflet of the tripartite membrane usually appeared discontinuous or globular after fixation in glutaraldehyde-osmium tetroxide. The DLS could be distinguished from all other cellular components and may represent a new organelle unique to spermatogenesis.

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Perspectives on golgi apparatus form and function

1991

J. Elec. Microsc. Tech.

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In 1898, Camillio Golgi reported a new cellular constituent with the form of an extensive intracellular network (the apparato reticolare interno), which now bears his name. However, the history of Golgi's apparatus is replete with controversy regarding its reality, what components of the cell should be included under its aegis, and what terminology should be used when referring to it. Electron microscopy has resolved many of these controversies and it is appropriate that this volume emphasize that aspect of Golgi apparatus discovery. The principal structural component of the Golgi apparatus is the stack of cisternae, or dictyosome. As determined both biochemically and at the level of electron microscopy, the dictyosome is a highly ordered and polarized structure. The maintenance of order within the stack is thought to result from either intercisternal bonding constituents, or filamentous structures (or both) that bridge the space between adjacent cisternae. Mechanisms proposed for movement of membrane and product into and out of the dictyosome (i.e., the Golgi apparatus stack) include a serial mode which functions exclusively by the formation, displacement, and loss of cisternae from the stack, and a parallel mode which functions exclusively by the movement of membrane, product, or precursor molecules directly into the peripheral edges of the cisternae. In the parallel mode, all cisternae can be accessed either singly or simultaneously, at least in theory, at any position within the stack. It is probable that both the serial and the parallel modes function concomitantly and need not be mutually exclusive. Finally, the peripheral tubules of the cisternae represent a major membranous constituent of the cell with potentially unique functions. These tubules interconnect cisternae of adjacent stacks and may represent the major site of receptors for the shuttle (i.e., parallel) type of transfer among cisternae. Peripheral tubules as extensions of the cisternal lumina into the cytoplasm presumably have other functions, but these, like the tubules themselves, have only rarely been accommodated into functional models of Golgi apparatus dynamics in secretion or membrane flow.

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A possible role for intercisternalelements in the formation of secretory vesicles in plant golgi apparatus

Cited by 31 publications

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TheGolgi Apparatus in Mammalian and Higher Plant Cells: A Comparison

TheGolgi Apparatus in Mammalian and Higher Plant Cells: A Comparison

Dictyosome‐like structures with cylindrical intersaccular connections (microtubules?) in guinea pig spermatocytes

Perspectives on golgi apparatus form and function

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